This invention relates to linear image sensors in which light propagating from an object, and incident imagewise on a photosensor array, signals an imagewise electrical output. This invention is related to an invention disclosed in application Ser. No. 627,499, filed herewith, by Ned J. Seachman the disclosure of which is incorporated herein by reference.
The art of producing arrays of photosensors, such as charge coupled devices (CCD), is currently in development. One form of CCD arrays now being produced is limited to 256 individual photosensors in a strip or linear array. For scanning an object, for example, a 9-inch wide document, and in order to resolve five line pairs per millimeter, at least 10 photosensor elements per millimeter are necessary. This requires 254 elements per inch. Thus, nine of the 256 element arrays must be placed in a line.
It is not readily feasible to fabricate these photosensor arrays such that the end elements of two successive arrays can be physically positioned so as to create an unbroken line of photosensor elements extending across a page.
It is an object of this invention to provide a novel technique for the optical superposition of physically offset lines of photosensor arrays to create the optical equivalent of one continuous line of such photosensors.
Another object is to provide such an arrangement in which a plurality of photosensor arrays can be disposed on a common image plane, simplifying the construction of the system.